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Why donít magnets stick to aluminum cans?
Magnets will only stick to certain things. Two pieces of metal may look the same to us, but if you could examine their individual atoms they might look very different. As you have noticed, some types of metal are strongly attracted magnets and some arenít. Metals that are strongly attracted to magnets have generally have individual atoms that each behave very much like tiny magnets. Whether or not an atom behaves this way depends on how the electrons that orbit the nucleus of the atom are arranged. The way that the atoms arrange themselves to become a solid metal can also influence how magnetic a material is. Whether enough of the little atomic magnets line up together to make a magnet strong enough to notice easily depends also on the temperature, since at high temperatures the atomic magnets tend to point random directions.
As you have probably already noticed, iron is very "magnetic" but aluminum is not. Now you know that this is due to differences in the properties and arrangements of the atoms in these metals. Unfortunately, without a little introduction to the quantum mechanical properties of these metals, we can't really explain why metals with different numbers of electrons per atom behave so differently.
Adam (+Mike W.)
(republished on 07/13/06)
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